[GIT PULL tip/core/rcu] RCU commits for v5.9

[GIT PULL tip/core/rcu] RCU commits for v5.9

[Paul E. McKenney]

Hello, Ingo!

This pull request contains the following changes:

1.	Documentation updates.

	https://lore.kernel.org/lkml/20200623000923.GA25047@paulmck-ThinkPad-P72

2.	Miscellaneous fixes.

	https://lore.kernel.org/lkml/20200623002128.GA25456@paulmck-ThinkPad-P72

3.	kfree_rcu updates.

	https://lore.kernel.org/lkml/20200624201200.GA28901@paulmck-ThinkPad-P72

4.	RCU tasks updates.

	https://lore.kernel.org/lkml/20200623002423.GA25869@paulmck-ThinkPad-P72

5.	Read-side scalability tests.

	https://lore.kernel.org/lkml/20200623002941.GA26089@paulmck-ThinkPad-P72

6.	SRCU updates.

	https://lore.kernel.org/lkml/20200623003310.GA26539@paulmck-ThinkPad-P72

7.	Torture-test updates.

	https://lore.kernel.org/lkml/20200623003731.GA26717@paulmck-ThinkPad-P72

All of these have been subjected to the kbuild test robot and -next
testing, and are available in the git repository based on v5.8-rc3 at:

  git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo

for you to fetch changes up to 13625c0a4074d3bab61b1dc70a828b574255f339:

  Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD (2020-06-29 12:03:15 -0700)

----------------------------------------------------------------
Arnd Bergmann (1):
      refperf: Work around 64-bit division

Ethon Paul (1):
      srcu: Fix a typo in comment "amoritized"->"amortized"

Frederic Weisbecker (1):
      tick/nohz: Narrow down noise while setting current task's tick dependency

Joel Fernandes (Google) (5):
      rcu/tree: Keep kfree_rcu() awake during lock contention
      rcu/tree: Skip entry into the page allocator for PREEMPT_RT
      rcu/tree: Make debug_objects logic independent of rcu_head
      rcuperf: Remove useless while loops around wait_event
      refperf: Add a test to measure performance of read-side synchronization

Jules Irenge (2):
      rcu: Replace 1 with true
      rcu/rcutorture: Replace 0 with false

Lihao Liang (1):
      rcu: Update comment from rsp->rcu_gp_seq to rsp->gp_seq

Madhuparna Bhowmik (1):
      trace: events: rcu: Change description of rcu_dyntick trace event

Marco Elver (1):
      torture: Pass --kmake-arg to all make invocations

Mauro Carvalho Chehab (10):
      docs: RCU: Convert checklist.txt to ReST
      docs: RCU: Convert lockdep-splat.txt to ReST
      docs: RCU: Convert lockdep.txt to ReST
      docs: RCU: Convert rculist_nulls.txt to ReST
      docs: RCU: Convert torture.txt to ReST
      docs: RCU: Convert rcuref.txt to ReST
      docs: RCU: Convert stallwarn.txt to ReST
      docs: RCU: Don't duplicate chapter names in rculist_nulls.rst
      rcu: Fix some kernel-doc warnings
      rcu: Fix a kernel-doc warnings for "count"

Paul E. McKenney (65):
      doc: Timer problems can cause RCU CPU stall warnings
      doc: Tasks RCU must protect instructions before trampoline
      mm/mmap.c: Add cond_resched() for exit_mmap() CPU stalls
      rcu: Add callbacks-invoked counters
      rcu: Add comment documenting rcu_callback_map's purpose
      rcu: Grace-period-kthread related sleeps to idle priority
      rcu: Priority-boost-related sleeps to idle priority
      rcu: No-CBs-related sleeps to idle priority
      rcu: Expedited grace-period sleeps to idle priority
      fs/btrfs: Add cond_resched() for try_release_extent_mapping() stalls
      rcu: Remove initialized but unused rnp from check_slow_task()
      rcu: Mark rcu_nmi_enter() call to rcu_cleanup_after_idle() noinstr
      lockdep: Complain only once about RCU in extended quiescent state
      rcu-tasks: Convert sleeps to idle priority
      rcu-tasks: Make rcu_tasks_postscan() be static
      rcu-tasks: Add #include of rcupdate_trace.h to update.c
      rcu-tasks: Conditionally compile show_rcu_tasks_gp_kthreads()
      rcu-tasks: Fix code-style issues
      rcuperf: Add comments explaining the high reader overhead
      torture: Add refperf to the rcutorture scripting
      refperf: Add holdoff parameter to allow CPUs to come online
      refperf: Hoist function-pointer calls out of the loop
      refperf: Allow decimal nanoseconds
      refperf: Convert nreaders to a module parameter
      refperf: Provide module parameter to specify number of experiments
      refperf: Dynamically allocate experiment-summary output buffer
      refperf: Dynamically allocate thread-summary output buffer
      refperf: Make functions static
      refperf: Tune reader measurement interval
      refperf: Convert reader_task structure's "start" field to int
      refperf: More closely synchronize reader start times
      refperf: Add warmup and cooldown processing phases
      refperf: Label experiment-number column "Runs"
      refperf: Output per-experiment data points
      refperf: Simplify initialization-time wakeup protocol
      refperf: Add read-side delay module parameter
      refperf: Adjust refperf.loop default value
      doc: Document rcuperf's module parameters
      refperf: Change readdelay module parameter to nanoseconds
      refperf: Add test for RCU Tasks Trace readers.
      refperf: Add test for RCU Tasks readers
      rcu-tasks: Fix synchronize_rcu_tasks_trace() header comment
      refperf: Rename RCU_REF_PERF_TEST to RCU_REF_SCALE_TEST
      refperf: Rename refperf.c to refscale.c and change internal names
      refscale: Change --torture type from refperf to refscale
      torture:  Remove qemu dependency on EFI firmware
      torture: Add script to smoke-test commits in a branch
      rcutorture: Add races with task-exit processing
      torture: Set configfile variable to current scenario
      rcutorture: Handle non-statistic bang-string error messages
      rcutorture: NULL rcu_torture_current earlier in cleanup code
      torture: Remove whitespace from identify_qemu_vcpus output
      torture: Add --allcpus argument to the kvm.sh script
      torture: Create qemu-cmd in --buildonly runs
      torture: Add a stop-run capability
      torture: Abstract out console-log error detection
      rcutorture: Check for unwatched readers
      torture: Correctly summarize build-only runs
      torture: Improve diagnostic for KCSAN-incapable compilers
      torture: Add more tracing crib notes to kvm.sh
      torture: Add kvm-tranform.sh script for qemu-cmd files
      torture: Dump ftrace at shutdown only if requested
      torture: Avoid duplicate specification of qemu command
      torture: Remove obsolete "cd $KVM"
      Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD

Peter Enderborg (1):
      rcu: Stop shrinker loop

Randy Dunlap (1):
      kernel/rcu/tree.c: Fix kernel-doc warnings

Sebastian Andrzej Siewior (2):
      rcu/tree: Use static initializer for krc.lock
      srcu: Avoid local_irq_save() before acquiring spinlock_t

Uladzislau Rezki (Sony) (12):
      rcu/tree: Repeat the monitor if any free channel is busy
      rcu/tree: Simplify KFREE_BULK_MAX_ENTR macro
      rcu/tree: Move kfree_rcu_cpu locking/unlocking to separate functions
      rcu/tree: cache specified number of objects
      rcu/tree: Maintain separate array for vmalloc ptrs
      rcu/tiny: support vmalloc in tiny-RCU
      rcu: Rename *_kfree_callback/*_kfree_rcu_offset/kfree_call_*
      mm/list_lru.c: Rename kvfree_rcu() to local variant
      rcu: Introduce 2 arg kvfree_rcu() interface
      rcu: Support reclaim for head-less object
      rcu: Introduce single argument kvfree_rcu() interface
      lib/test_vmalloc.c: Add test cases for kvfree_rcu()

Wei Yang (5):
      rcu: Initialize and destroy rcu_synchronize only when necessary
      rcu: Simplify the calculation of rcu_state.ncpus
      rcu: gp_max is protected by root rcu_node's lock
      rcu: grplo/grphi just records CPU number
      rcu: grpnum just records group number

Zou Wei (1):
      locktorture: Use true and false to assign to bool variables

 .../RCU/Design/Requirements/Requirements.rst       |   7 +-
 Documentation/RCU/{checklist.txt => checklist.rst} |  17 +-
 Documentation/RCU/index.rst                        |   9 +
 .../RCU/{lockdep-splat.txt => lockdep-splat.rst}   | 109 ++--
 Documentation/RCU/{lockdep.txt => lockdep.rst}     |  12 +-
 Documentation/RCU/rculist_nulls.rst                | 200 ++++++
 Documentation/RCU/rculist_nulls.txt                | 172 -----
 Documentation/RCU/{rcuref.txt => rcuref.rst}       | 199 +++---
 Documentation/RCU/{stallwarn.txt => stallwarn.rst} |  62 +-
 Documentation/RCU/{torture.txt => torture.rst}     | 117 ++--
 Documentation/admin-guide/kernel-parameters.txt    |  68 ++
 Documentation/locking/locktorture.rst              |   2 +-
 MAINTAINERS                                        |   4 +-
 fs/btrfs/extent_io.c                               |   2 +
 include/linux/rculist.h                            |   2 +-
 include/linux/rculist_nulls.h                      |   2 +-
 include/linux/rcupdate.h                           |  53 +-
 include/linux/rcupdate_trace.h                     |   4 +-
 include/linux/rcutiny.h                            |  20 +-
 include/linux/rcutree.h                            |   2 +-
 include/linux/torture.h                            |   5 +
 include/trace/events/rcu.h                         |  19 +-
 kernel/locking/lockdep.c                           |   4 +-
 kernel/locking/locktorture.c                       |  14 +-
 kernel/rcu/Kconfig.debug                           |  19 +
 kernel/rcu/Makefile                                |   1 +
 kernel/rcu/rcuperf.c                               |  25 +-
 kernel/rcu/rcutorture.c                            | 119 +++-
 kernel/rcu/refscale.c                              | 717 +++++++++++++++++++++
 kernel/rcu/srcutree.c                              |  16 +-
 kernel/rcu/tasks.h                                 |  37 +-
 kernel/rcu/tiny.c                                  |   7 +-
 kernel/rcu/tree.c                                  | 407 ++++++++----
 kernel/rcu/tree.h                                  |  15 +-
 kernel/rcu/tree_exp.h                              |   2 +-
 kernel/rcu/tree_plugin.h                           |   4 +-
 kernel/rcu/tree_stall.h                            |   9 +-
 kernel/rcu/update.c                                |  16 +-
 kernel/time/tick-sched.c                           |  22 +-
 kernel/torture.c                                   |   6 +-
 lib/test_vmalloc.c                                 | 103 ++-
 mm/list_lru.c                                      |   6 +-
 mm/mmap.c                                          |   1 +
 net/core/sock.c                                    |   4 +-
 .../testing/selftests/rcutorture/bin/configinit.sh |   4 +-
 .../selftests/rcutorture/bin/console-badness.sh    |  16 +
 .../testing/selftests/rcutorture/bin/functions.sh  |  23 +-
 tools/testing/selftests/rcutorture/bin/jitter.sh   |   6 +
 .../testing/selftests/rcutorture/bin/kvm-build.sh  |   6 +
 .../selftests/rcutorture/bin/kvm-check-branches.sh | 108 ++++
 .../rcutorture/bin/kvm-recheck-refscale.sh         |  71 ++
 .../selftests/rcutorture/bin/kvm-recheck.sh        |  20 +-
 .../selftests/rcutorture/bin/kvm-test-1-run.sh     |  27 +-
 .../selftests/rcutorture/bin/kvm-transform.sh      |  51 ++
 tools/testing/selftests/rcutorture/bin/kvm.sh      |  19 +-
 .../selftests/rcutorture/bin/parse-console.sh      |  27 +-
 .../selftests/rcutorture/configs/refscale/CFLIST   |   2 +
 .../selftests/rcutorture/configs/refscale/CFcommon |   2 +
 .../rcutorture/configs/refscale/NOPREEMPT          |  18 +
 .../selftests/rcutorture/configs/refscale/PREEMPT  |  18 +
 .../rcutorture/configs/refscale/ver_functions.sh   |  16 +
 61 files changed, 2395 insertions(+), 680 deletions(-)
 rename Documentation/RCU/{checklist.txt => checklist.rst} (98%)
 rename Documentation/RCU/{lockdep-splat.txt => lockdep-splat.rst} (54%)
 rename Documentation/RCU/{lockdep.txt => lockdep.rst} (96%)
 create mode 100644 Documentation/RCU/rculist_nulls.rst
 delete mode 100644 Documentation/RCU/rculist_nulls.txt
 rename Documentation/RCU/{rcuref.txt => rcuref.rst} (50%)
 rename Documentation/RCU/{stallwarn.txt => stallwarn.rst} (88%)
 rename Documentation/RCU/{torture.txt => torture.rst} (76%)
 create mode 100644 kernel/rcu/refscale.c
 create mode 100755 tools/testing/selftests/rcutorture/bin/console-badness.sh
 create mode 100755 tools/testing/selftests/rcutorture/bin/kvm-check-branches.sh
 create mode 100755 tools/testing/selftests/rcutorture/bin/kvm-recheck-refscale.sh
 create mode 100755 tools/testing/selftests/rcutorture/bin/kvm-transform.sh
 create mode 100644 tools/testing/selftests/rcutorture/configs/refscale/CFLIST
 create mode 100644 tools/testing/selftests/rcutorture/configs/refscale/CFcommon
 create mode 100644 tools/testing/selftests/rcutorture/configs/refscale/NOPREEMPT
 create mode 100644 tools/testing/selftests/rcutorture/configs/refscale/PREEMPT
 create mode 100644 tools/testing/selftests/rcutorture/configs/refscale/ver_functions.sh

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Sebastian Andrzej Siewior]

On 2020-07-14 10:27:01 [-0700], Paul E. McKenney wrote:
> Joel Fernandes (Google) (5):
>       rcu/tree: Skip entry into the page allocator for PREEMPT_RT

If it is too late to drop this then I am going send a revert okay?

Sebastian

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Paul E. McKenney]

On Tue, Jul 14, 2020 at 08:14:26PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-07-14 10:27:01 [-0700], Paul E. McKenney wrote:
> > Joel Fernandes (Google) (5):
> >       rcu/tree: Skip entry into the page allocator for PREEMPT_RT
> 
> If it is too late to drop this then I am going send a revert okay?

I believe that Ulad and Joel are working on an update.

Now that you mention it Ulad and Joel, how is this coming along?

							Thanx, Paul

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Sebastian Andrzej Siewior]

On 2020-07-14 11:27:32 [-0700], Paul E. McKenney wrote:
> I believe that Ulad and Joel are working on an update.

I expressed multiple times that I am unhappy with the raw_spinlock_t
which both want to keep. It is important to be future proof but at the
same time I am not sure if they know how many in-hardirq kmalloc() or
kfree() invocation we have as of today in PREEMPT_RT.
I also had a patch in my series to keep the lock/unlock path symmetrical
and it I think that I the only one that is missing it.

> 							Thanx, Paul

Sebastian

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Uladzislau Rezki]

On Tue, Jul 14, 2020 at 09:02:53PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-07-14 11:27:32 [-0700], Paul E. McKenney wrote:
> > I believe that Ulad and Joel are working on an update.
>
> I expressed multiple times that I am unhappy with the raw_spinlock_t
> which both want to keep. It is important to be future proof but at the
> same time I am not sure if they know how many in-hardirq kmalloc() or
> kfree() invocation we have as of today in PREEMPT_RT.
>
It is not about counting how many times kfree_rcu() gets called from
the hard IRQ context for RT kernel. In fact it is about breaking of
such possibility if a conversion to spinlock_t is done. Is not it?

As a result the revert would change a behavior of the API function,
that is used to accept such usage. That is a motivation.

--
Vlad Rezki

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Uladzislau Rezki]

On Tue, Jul 14, 2020 at 11:27:32AM -0700, Paul E. McKenney wrote:
> On Tue, Jul 14, 2020 at 08:14:26PM +0200, Sebastian Andrzej Siewior wrote:
> > On 2020-07-14 10:27:01 [-0700], Paul E. McKenney wrote:
> > > Joel Fernandes (Google) (5):
> > >       rcu/tree: Skip entry into the page allocator for PREEMPT_RT
> > 
> > If it is too late to drop this then I am going send a revert okay?
> 
> I believe that Ulad and Joel are working on an update.
> 
> Now that you mention it Ulad and Joel, how is this coming along?
> 
Yes. I have made a proposal with dropping the lock. I do not see
any issues by doing that. I will upload a patch soon.

--
Vlad Rezki

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Paul E. McKenney]

On Tue, Jul 14, 2020 at 09:02:53PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-07-14 11:27:32 [-0700], Paul E. McKenney wrote:
> > I believe that Ulad and Joel are working on an update.
> 
> I expressed multiple times that I am unhappy with the raw_spinlock_t
> which both want to keep. It is important to be future proof but at the
> same time I am not sure if they know how many in-hardirq kmalloc() or
> kfree() invocation we have as of today in PREEMPT_RT.
> I also had a patch in my series to keep the lock/unlock path symmetrical
> and it I think that I the only one that is missing it.

Are you good with giving Ulad a few days to produce his patch?

We do have at least a week or two before the merge window opens,
after all.

						Thanx, Paul

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Sebastian Andrzej Siewior]

On 2020-07-14 13:53:26 [-0700], Paul E. McKenney wrote:
> Are you good with giving Ulad a few days to produce his patch?

Yes, why not. 

> 						Thanx, Paul
Sebastian

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Paul E. McKenney]

On Tue, Jul 14, 2020 at 10:17:34PM +0200, Uladzislau Rezki wrote:
> On Tue, Jul 14, 2020 at 11:27:32AM -0700, Paul E. McKenney wrote:
> > On Tue, Jul 14, 2020 at 08:14:26PM +0200, Sebastian Andrzej Siewior wrote:
> > > On 2020-07-14 10:27:01 [-0700], Paul E. McKenney wrote:
> > > > Joel Fernandes (Google) (5):
> > > >       rcu/tree: Skip entry into the page allocator for PREEMPT_RT
> > > 
> > > If it is too late to drop this then I am going send a revert okay?
> > 
> > I believe that Ulad and Joel are working on an update.
> > 
> > Now that you mention it Ulad and Joel, how is this coming along?
> > 
> Yes. I have made a proposal with dropping the lock. I do not see
> any issues by doing that. I will upload a patch soon.

Looking forward to seeing it!

							Thanx, Paul

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Ingo Molnar]

* Paul E. McKenney <paulmck@kernel.org> wrote:

> Hello, Ingo!
> 
> This pull request contains the following changes:
> 
> 1.	Documentation updates.
> 
> 	https://lore.kernel.org/lkml/20200623000923.GA25047@paulmck-ThinkPad-P72
> 
> 2.	Miscellaneous fixes.
> 
> 	https://lore.kernel.org/lkml/20200623002128.GA25456@paulmck-ThinkPad-P72
> 
> 3.	kfree_rcu updates.
> 
> 	https://lore.kernel.org/lkml/20200624201200.GA28901@paulmck-ThinkPad-P72
> 
> 4.	RCU tasks updates.
> 
> 	https://lore.kernel.org/lkml/20200623002423.GA25869@paulmck-ThinkPad-P72
> 
> 5.	Read-side scalability tests.
> 
> 	https://lore.kernel.org/lkml/20200623002941.GA26089@paulmck-ThinkPad-P72
> 
> 6.	SRCU updates.
> 
> 	https://lore.kernel.org/lkml/20200623003310.GA26539@paulmck-ThinkPad-P72
> 
> 7.	Torture-test updates.
> 
> 	https://lore.kernel.org/lkml/20200623003731.GA26717@paulmck-ThinkPad-P72
> 
> All of these have been subjected to the kbuild test robot and -next
> testing, and are available in the git repository based on v5.8-rc3 at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo
> 
> for you to fetch changes up to 13625c0a4074d3bab61b1dc70a828b574255f339:
> 
>   Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD (2020-06-29 12:03:15 -0700)

>  61 files changed, 2395 insertions(+), 680 deletions(-)

Pulled into tip:core/rcu, thanks a lot Paul!

I assume the fix Uladzislau Rezki is working on will resolve Sebastian 
Andrzej Siewior's objections?

Thanks,

	Ingo

Re: [GIT PULL tip/core/rcu] RCU commits for v5.9

[Paul E. McKenney]

On Fri, Jul 31, 2020 at 12:20:57AM +0200, Ingo Molnar wrote:
> 
> * Paul E. McKenney <paulmck@kernel.org> wrote:
> 
> > Hello, Ingo!
> > 
> > This pull request contains the following changes:
> > 
> > 1.	Documentation updates.
> > 
> > 	https://lore.kernel.org/lkml/20200623000923.GA25047@paulmck-ThinkPad-P72
> > 
> > 2.	Miscellaneous fixes.
> > 
> > 	https://lore.kernel.org/lkml/20200623002128.GA25456@paulmck-ThinkPad-P72
> > 
> > 3.	kfree_rcu updates.
> > 
> > 	https://lore.kernel.org/lkml/20200624201200.GA28901@paulmck-ThinkPad-P72
> > 
> > 4.	RCU tasks updates.
> > 
> > 	https://lore.kernel.org/lkml/20200623002423.GA25869@paulmck-ThinkPad-P72
> > 
> > 5.	Read-side scalability tests.
> > 
> > 	https://lore.kernel.org/lkml/20200623002941.GA26089@paulmck-ThinkPad-P72
> > 
> > 6.	SRCU updates.
> > 
> > 	https://lore.kernel.org/lkml/20200623003310.GA26539@paulmck-ThinkPad-P72
> > 
> > 7.	Torture-test updates.
> > 
> > 	https://lore.kernel.org/lkml/20200623003731.GA26717@paulmck-ThinkPad-P72
> > 
> > All of these have been subjected to the kbuild test robot and -next
> > testing, and are available in the git repository based on v5.8-rc3 at:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo
> > 
> > for you to fetch changes up to 13625c0a4074d3bab61b1dc70a828b574255f339:
> > 
> >   Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD (2020-06-29 12:03:15 -0700)
> 
> >  61 files changed, 2395 insertions(+), 680 deletions(-)
> 
> Pulled into tip:core/rcu, thanks a lot Paul!
> 
> I assume the fix Uladzislau Rezki is working on will resolve Sebastian 
> Andrzej Siewior's objections?

One way or another, yes.  We have several options, but the nicest one
requires changes outside of RCU, so cannot be carried out in time for the
upcoming merge window.  If that fails, we have other less-nice options
that -can- be confined to RCU, at least in the short term.

But one way or another, the issue that Sebastian raised will be resolved.

							Thanx, Paul